This invention relates to an information recording medium adapted to be capable of accurately detecting the recording and/or reproduction starting position and to an information recording-reproducing method and apparatus therefor.
It is well known to record information on a recording medium having a plurality of information tracks by the use of magnetism, a light beam or the like. A disc-like shape, a card-like shape, a tape-like shape, etc. are known as the shapes of such recording medium.
Now, when information is to be recorded on the information tracks of such medium with a light beam or a magnetic flux being stopped down by an optical head or a magnetic head, to record the information on a desired track, it is necessary to confirm whether the track is the desired track before the recording operation. One method was to pre-record a track number on that area of the track on which the information is to be recorded (hereinafter referred to as the requisite recording area) by some modulation system (for example, the FM modulation system), read this track number and thereby confirm the track.
Particularly as regards the track number, the assignee of the present invention filed an application which covers an embodiment in which the same information, i.e., the track number, is repetitively recorded with the fact being taken into account that reproduction cannot be accomplished because of dust or injury on the recording medium.
So, it becomes necessary to confirm the position at which recording of the track is started, that is, the first position of the recording area, after the desired track could be confirmed by said means. However, where a plurality of identical track numbers are continuously provided for one track as described above, depending on the position at which the track number that could be confirmed is provided, the distance from the position at which that track was confirmed to the first position of the requisite recording area is determined. In other words, the position at which the track number can be confirmed is not always a fixed position and therefor, the distance from the position at which the track was confirmed to the first position of writing is not always constant. Accordingly, again in such a case, it is desired that the recording starting position can be accurately detected.
Next, again in a case where information recorded in the recording area is to be reproduced, it is desired that the reproduction starting position be known accurately. So, it would occur to one to record a synchronizing mark before the information of the recording track, and repetitively record the synchronizing mark with a case taken into account where the synchronizing mark cannot be reproduced because of injury or the like. Again in this case, however, the distance from the point at which the synchronizing mark is detected to the reproduction starting position is not always constant and therefore, it would occur to one to include means such as caption code in the information and recognize the reproduction starting position. In this case, the presence or absence of a detection error is determined by whether the caption code is properly recognized, and it is difficult to know the reproduction starting position at stable accuracy.
It is therefore a first object of the present invention to provide an information recording medium on which a plurality of marks for discriminating between information tracks, such as track numbers, are continuously provided in the other area of the information tracks than the requisite recording area and in which the information recording starting position can be accurately detected without any error.
In the information recording meidum according to the present invention, at least marks for discriminating between information tracks and a mark indicative of the information from a position at which each of the marks is provided to the recording starting position are provided in an information block, and a plurality of such information blocks are continuously provided in the other area of the information tracks than the requisite recording area. Therefore, in whatever information block the information track is confirmed, the information from that position to the recording starting position is read at a time and thus, recording can be accomplished at an accurate position.
In this case, if the construction is such that even during reproduction of the record, the reproduction of the portion in which the information block is included is effected, accurate detection of the reproduction starting position also becomes possible by this information block.
It is a second object of the present invention to provide an information recording-reproducing method and apparatus for accurately recording and/or reproducing information by the use of such an information recording medium.
It is a third object of the present invention to provide an information recording-reproducing method and apparatus in which during recording, information for discriminating the reproduction starting position is recorded on a recording track and during reproduction, the reproduction starting position can be accurately detected by the discriminating information.
It is a fourth object of the present invention to provide an information recording-reproducing method and apparatus in which when use is made of an information recording medium on which is pre-recorded position discriminating information having information indicative of the recording starting position, even if this prerecorded position discriminating information is not reproduced during the reproduction of the record, the same position discriminating information as said position discriminating information, together with the recording information, is recorded on a recording track during information recording, and during reproduction also, the reproduction starting position can be accurately detected by the position discriminating information recorded on said recording track.